Method of brightening fabrics with sulfonated dibenzothiophene dioxide derivatives



United States Patent METHOD OF BRIGHTENING FABRICS WITH SUL- FONATEDDIBENZOTHIOPHENE DIOXIDE DE- RIVATIVES Mario Scalera, Somerville, andDale R. Eberhart, Middlesex, N. J., assignors to American CyanamitlCompany, New York, N. Y., a corporation of Maine No Drawing. ApplicationMay 16, 1951, Serial No. 226,732

9 Claims. (Cl. 117-335) This application is concerned with opticalbleaching and brightening and especially with new derivatives ofbenzothiophene distinguished by their remarkable utility for thispurpose. More specifically the invention relates to water-solublederivatives of acylated 3,7-diaminodibenzothiophene dioxides, methods orwhitening and brightening fabrics therewith and the fabrics so treated.This is a continuation in part of our prior copending application SerialNo. 168,392, filed June 15, 1950 now United States Patent No. 2,563,493,dated August 7, 1951, which in turn is a continuationin-part of ourcopending application Serial No. 45,425 filed August 20, 1948 now UnitedStates Patent No. 2,563,795, dated August 7, 1951.

In particular, the invention utilizes a novel group of compounds whichare sulfonated derivatives of compounds containing the nucleus:

in which R and R are radicals of the aliphatic and aromatic series.

It is well known that cellulosic materials tend to develop anundesirable yellowish cast with age. Unfortunately it cannot be removedby ordinary simple bleaching or scouring. Development of this yellownessis aggravated among other reasons, by continued exposure to light,weathering and repeated laundermgs. It is, therefore, particularlytroublesome in plastics and textile fabrics that must be subjected tothese COl'ldltions.

For many years, it has been the practice to attempt to conceal thisyellowing by the use of blue pigments or dyes, to neutralize thecomplementary yellow color of the cellulose. For this purpose, the useof blue pigments, such as Ultramarine or Alkali Blue, or of fugitiveblue dyestuffs, has become common practice in paper manufacture andlaundry operations.

While these blue coloring matters are often temporarily effective, theyare subject to serious disadvantages. For example, addition of a bluecolor to a yellow does not produce pure white, but rather a gray. Thegreater the intensity of the original yellow, the more blu'mg necessaryto hide it, and the darker in cast the resulting gray. Further, unlessan exact color balance is struck, the finished product is not even graybut may actually be blue.

In 1929, P. Krais (Melliands Textilberichte, 1929, pp. 468-9) suggestedusing, not a blue coloring matter to absorb yellow light, but aesculin,a fluorescent substance capable of emitting blue light. Thus, theyellowing effect, which consists in absorbing the blue light, is trulydestroyed by a substance which emits the blue light lost, resulting intrue white instead of gray.

No widespread acceptance of this proposal occurred. This was largely dueto the lack of acceptable materials. To be suitable for this purpose, acompound should possess the properties of being:

1. Colorless in white light;

2. Strongly fluorescent under the influence of ultraviolet rays such asare present in sunlight;

3. Fluorescing blue-white;

Hce

4. sufficiently substantive to be absorbed from very low concentrations;5. Resistant to common agents such as soap, chlorine,

and light; 6. Free from the tendency to decompose to colored products;7. Reasonably low in cost of production in proportion to effectiveness;8. Free from tendency to discolor soap or detergents when incorporatedtherein. Aesculin, suggested by Krais, fails completely as to 4 and 5and badly as to 7. None of the available materials were suitable in allof these properties. It was particularly difiicult to satisfy the third,fourth, fifth and eighth requirements.

It is, therefore, a principal object of the present invention to developnew compounds suitable for use as optical bleaching agents and combiningthe above-listed properties. This object has been found to beaccomplished, with an elfectiveness both surprising and unpredictable,in the sulfonic acids of acylated 3,7-diaminodibenzothiophene dioxideand its nuclear substitution products. These compounds combine to anamazing degree the various desirable properties of affinity, highstrength, physical and chemical stability, substantivity, andfluorescent hue. Since current theories of substantivity andfluorescence are somewhat vague, the present invention is not restrictedto any particular theory of action.

The compounds herein disclosed will effectively neutralize theyellowness of cellulosic textiles even when applied from very minuteconcentrations. On the other hand, they can be applied from relativelyconcentrated solution when it is desired to produce greatly enhancedwhiteness and brilliance of discharge effects. The application of theseagents may be carried out in a separate rinse bath; or they may be usedin conjunction with the soaping operation; or the agents may beincorporated in the soap or detergent and marketed in that form toenhance the cleansing and whitening action of said detergent. Thelatter, in fact, is one of the preferred modes of utilization of ourcompounds, which are particularly suited for marketing in this man nor,in admixture with detergents.

The compounds of the present invention possess a valuable property notshared with most other whitening agents which have been proposed in theart for similar purposes. They do not cause a discoloration of thedetergent itself when mixed therewith.

Many brighteners of other types, which are excellent in their whiteningeifect on the cloth to which they are eventually applied, neverthelesssuifer from the serious drawback of imparting a yellow discoloration tothe detergent with which they are admixed, even in the customarily smallamounts of .001 to 1% by weight. This is commercially very undesirable,and in fact detergents of pure white appearance are so stronglypreferred in the trade that certain auxiliary agents, such as methylumbelliferone, are often incorporated directly therein for the solepurpose of enhancing the whiteness of the detergent itself.

It is therefore a particularly striking advantage of the brighteners ofthe present invention, that they do not impair the whiteness of soliddetergents. Actually in many cases they may enhance it in a mannersimilar to the above mentioned methyl umbelliferone; thus in effectcombining two separate and highly useful propertieswhitening of thedetergent and whitening of the clothin a single compound.

Another notable advantage of these compounds over products used by theprior art for similar purposes is their superior chemical stability,particularly to chlorine bleaches. The importance of such property isquickly realized when one considers that chlorine bleaching is anoperation almost universally associated with laundering or scouring.

These compounds also possess valuable properties other than as bleachingor whitening agents for white goods. For example, they may be used oncolored textiles to enhance the color effect of many different dyes andpigments. Their mode of application for this purpose may vary: they maybe used in a preliminary treatment of the fabric, applied with the dye,or applied as an after treatment.

, Utilization of the compounds of this invention is not limited totreatment of textile fabrics. They may also be beneficially used in themanufacture of paper and felt products and in making transparent ortranslucent sheets or pellicles or cellulose or other origin. Theirusefulness ride; adipyl chloride; crotonyl chloride; ethoxyacetylchloride; maleic anhydride; benzoyl and phenylacetyl chloride and thealkyl, halo, nitro, amino, and oxygenated substitution products thereof;the naphthoyl chlorides; phthalic anhydride; 2-hydroxy-3-naphthoylchloride;

,phenoxyacetyl chloride; cinnamic chloride; substituted carbanilylchlorides; hydrocinnamoyl chloride; hexahydro- ,benzoyl chloride;cyclohexylacetyl chloride; furoyl chloride; nicotinyl chloride;picolinyl chloride; diethyl can .bamyl chloride; cinchoninic acidchloride; and thiophenealpha-carboxylic acid chloride. These acylatingagents may be employed in a neutral or basic organic solvent or in anaqueous medium. A difunctional acylating agent, such as phosgene, may beused to link together two molecules of benzidine sulfone. By the properchoice of reagents and conditions, the 3- and 7- nitrogens may besubstituted by the same or different acyl groups. Alternately, anunsulfonated 3,7-diarninodibenzothiophene dioxide and its abovementioned substitution products may be acylated with any of theacylating agents mentioned dioxide may be sulfonated in a second step.

Thus it is evident that the sulfonic acid groups, which are necessaryfor the practical fulfillment of the invention, may be present in eitherthe dibenzothiophene or the acyl nuclei, and that they may be introducedeither before or after the acylation step. This will be furtherillustrated in conjunction with several specific examples given below.

.above, and the resulting 3,7-diacylaminodibenzothiophene acid, withoutprevious isolation. The ensuing sulfonation is advantageously conductedat room temperature or below. It is desirable to cool while thechlorosulfonic acid is added; frequently the sulfonation can then becompleted around room temperature. When the sulfonation is finished, thereaction mixture is drowned in ice and water, and the solvent removed bysteam distillation. The product is isolated in good yield and purity,either as the free sulfonic acid or a salt thereof. The salts are ofequal importance to the free acids and are understood to be theirobvious equivalents.

In the case where it is desired to acylate after sulfonation, one maystart with an aminosulfonic acid of the dibenzothiophene dioxide series,obtainable for instance by the processes described in the copendingapplications of Long and Tsang, Serial N0. 168,379, filed June 15, 1950,United States Patent No. 2,590,632, and Tsang, Serial No. 184,707, filedSeptember 13, 1950, now United States Patent No. 2,620,343. With theseamino sulfonic acids, it is advantageous to perform the'acylation in anorganic solvent with the aid of a tertiary amine or of substitutedguanidine, according to the procedure of the copending applications ofForster and Scalera, Serial No. 153,988, filed April 4, 1950, now UnitedStates Patent No. 2,573,652, and Eberhart and Lecher, Serial No.153,992, filed April 4, 1950, now United States Patent No. 2,580,234.

It has been observed that when it is desired to produce a sulfonatedderivative of this class bearing the sulfonic groups in thedibenzothiophene dioxide ring, the process of sulfonation beforeacylation, offers a sure way of obtaining the desired compound. Theprocess of sulfonation following acylation generally produces sulfonatedderivatives which carry the sulfonic group or groups in the outer acylrings, provided, of course, such acyl rings are of the aromatic type,and capable of sulfonation. Thus, by the two processes hereinbeforedescribed it is possible to prepare all types of products broadlydisclosed in the present application.

The invention will be discussed more fully in conjunction with theaccompanying examples which are furnished by way of illustration. Exceptas otherwise noted all parts are parts by weight, and all temperaturesare in degrees centigrade.

Example 1 nso 803E cum-Goon \S NHC 000 on; Oz

The process for acylation before sulfonation is one of wideapplicability. For the acylation the best choice of reaction conditionsfor a given case is somewhat dependent on the reactivity and stabilityof the reactants. It

'has been found that it is generally convenient to carry out To 3 partsby weight of dry 3,7-diaminodibenzothiophene-5,5'-dioxide-2,8-disodiumsulfonate are added 7.7 parts of p-anisoyl chloride and A to /2 part ofpyridine. The mixture is stirred and heated to l50-l 60 C., cooled,diluted with acetone, filtered, Washed, suspended in hot, dilute NazCOasolution, filtered, washed and dried to give a light brown productdissolving in water to a strongly blue fluorescent solution. The productis valuable for whitening cellulosic and other materials.

Example 2 If, in the procedure of the above example, theanisoyl chlorideis substituted by p-toluyl chloride, the di-p-toluyl derivative isobtained as a light yellow product. It has a similar shade offluorescence.

Example 3 5 S0311 S0311 CHsOQCONH \s NHCOGOGH:

of isolating the product, which is obtained in high purity and goodyield. For this reaction, it has been found that nitrohydrocarbons, suchas nitromethane, nitropropane, and nitrobenzene, are highly suitablesolvents; after completion of the reaction, the solvent is easilyremoved by steam distillation.

It has also been found possible, by operating in a nitrohydrocarbon suchas nitrobenzene, to first acylate the free dibenzothiophene dioxidediamine, and then to proceed immediately to the sulfonation withchlorosulfonic To 12.3 parts of 3,7-diaminodibenzothiophene-5,5'-dioxidein parts of nitrobenzene are added 20.4 parts of p-anisoyl chloride atl00-l50 C. The mixture is stirred at C. until primary amino groups canno longer be detected, then cooled and 117 parts of chlorosulfonic acidadded during 30 minutes at 1020 C. The mixture is stirred at l820 C.until the reaction is complete. The mixture is drowned in a mixture ofice and 50 g. salt, filtered, the cake neutralized .and nitrobenzenesteamed off, or the drowned mixture may be neutralized directly Example4 HQ: 03H

OONH S NHOC 02 3,7-diaminodibenzothiophenedioxide-Z,8-disulfonic acid isdissolved in dilute sulfuric acid and treated with triethylamine. Thetriethylarnine salt crystallizes from the cold solution, and is filteredand dried. A slurry of 30.4 parts of the resulting salt in 133 parts ofchlorobenzene and 30.3 parts of triethylarnine is heated under refluxwith stirring and to it is added during about 30 minutes 27.7 parts ofortho-ethoxybenzoyl chloride. Thereaction mixture is heated under refluxfor four hours and then treated with an additional portion of 30.3 partsof triethylamine and 27.7 parts of ortho-ethoxybenzoyl chloride.Refluxing and stirring are continued overnight. The chlorobenzene andtriethylamine are removed by steam distillation after adding suflicientsodium carbonate to render the mixture alkaline to brilliant yellow. Theproduct is isolated in excellent yield in the usual manner byfiltration, washing with 2% brine and drying.

Example 5 0 CH3 CHsO chlorobenzene.

A slurry of 122 parts of3,7-diaminodibenzothiophenedioxide-2,8-disulfonic acid, 157 parts ofpyridine, and 1110 parts of monochlorobenzene is heated at reflux andtreated with a solution of 185 parts of 2,4-dimethoxybenzoyl chloride in220 parts of chlorobenzene. three hours at reflux, 250 parts of sodiumcarbonate are added, and the mixture is steamed free of pyridine andchlorobenzene, salted with 5% its weight of sodium chloride, cooled to15 C. and filtered. The cream-colored cake after washing with 2% brineand drying at 90 C. represents an excellent yield of 3,7 di (2,4dimethoxybenzoylarnino) dibenzothiophenedioxide 2,8 disodium suli'onate.

Example 6 0 ONE NHOC S H5020 OCzHa H5020 002115 The trimethylainine saltof 3,7-diaminodibenzothiophenedioxide-Z,S-disulfonic acid is prepared bytreatment with excess of 30% aqueous trimethylamine solution andevaporation to dryness. The salt is acylated by heating with2,4-diethoxybenzoyl chloride in chlorobenzene, as described in Example2. The mixture is then treated with soda ash and steam distilled toremove chlorobenzene and trimethylamine. The addition of sodium chloridesalts out an excellent yield of3,7-di(2,4-diethoxybenzoylamino)dibenzothiophenedioxide-2,S-disulfonicacid.

Example 7 HO: SOaH 0 ONE 8 NHC O O2 .06 H5 I After3,7-diaminodibenzothiophenedioxide-Z,S-disulfonic acid is dissolved indilute sulfuric acid and treated with triethylamine. The triethylaminesalt crystallizes from the cold solution, and .is filteredand dried.15.2 parts of the salt is slurried in 10 parts of pyridine and parts ofAfter heating to reflux, the mixture is gradually treated with 20.2"parts of o-phenyl-benzoyl chloride. Heating and stirring are continueduntil acylation is complete. The resulting slurry is made alkaline withaqueous sodium carbonate and steam distilled .to remove the solvents.The product is then salted out with sodium chloride, filtered, washedwith brine, and dried.

CHsOQC GOOCH;

A mixture of 10.4 parts of pyridine,"8-3 parts of chlorobenzene, and10.1 parts of the triethylamine salt of 3,7-diaminodibenzothiophenedioxide-Z,8-disulfonic acid is heated to refluxand treated with 15.9 parts of o-carbomethoxybenzoyl chloride. Whenacylation is completed, the solid product is separated, dissolved inaqueous sodium carbonate and salted out with sodium chloride. It is thenfiltered and dried.

Example 9 Ga sOCHzCONH NHCOCHaOCeHI A mixture of 1.45 parts of.chlorobenzene, 16 parts of pyridine, and 15.2 parts of thetriethylamine salt of 3,7- diaminodibenzothiophenedioxide-2,8-disulfqnicacid is heated to reflux and gradually treated with 15.4 parts ofphenoxyacetyl chloride. When acylationis complete-the mixture is cooled,made alkaline with sodiumcarbonate, and subjected to steam distillation.The product is salted out in the usual way and filtered.

Example ,1!)

Bots.

Example 11 I HOsS. SQzH CHaCH=CHCOHN NHCO CH=CHCHI A mixture of parts offchlorobenzene, 16 parts of pyridine; and 15.2 parts of thetriethylaminesalt oi 3,7- diaminodibenzothiophenedioxide-Z,S-disulfonit:acid; is heated to reflux and treated gradually with 10.8 parts ofcrotonyl chloride. The mixture is stirred and heated until acylation iscomplete, then made alkaline with sodium carbonate solution and steamdistilled to removev the solvents. The addition of sodiumlchloridesaltsout the product as a bright yellow solid, which is'filtered and dried.

Example 12 HO GuHflOn-OCOHN A slurry of 7.6 parts of the triethylaminesalt of 3,7- diaminodibenzothiophenedioxide-Z,8-disulfonic acid, inparts of pyridine, and 225 parts of chlorobenzene, is heated to 80 andtreated slowly with 12.7 parts of p-phenylsulfonylbenzoyl ch1oride.-Acylation is completed at reflux temperature, the mixture then beingtreated with aqueous sodium carbonate and steam distilled free ofpyridine. The yellow product is salted out by the addition of sodiumchloride, filtered, washed, and dried.

Example 13 Example 14 i The procedure of the preceding example isfollowed, 'using m-methylsulfonylbenzoyl chloride instead of thepisome'r. The product is similar.

Example 15 A mixture of 15.2 parts of the triethylamine salt, preoutwith sodium chloride and filtered and HOaS- CsHsCH=CHCOHN S 0:

0:11 7 NHO o-Osomm Example 17 g The l-naphthoylisomer is prepared in thesame manner, substituting l-naphthoic acid for the Z-naphthoic acid.

S0:H Y mace-Osman.

Its properties are essentially similar.

Example 18 A solution is prepared from 26.3 parts ofdi-o-tolylguanidine, 11.9 parts of concentrated hydrochloric acid, andwater to the volume of 200 parts of water. This is slowly added to asolution prepared by adding 20.3 parts of3,7-diaminodibenzothiophenedioxide-Z,8-disulfonic acid to parts ofwater, neutralizing with 5N sodium hydroxide solution, and diluting tothe volume of 200 parts of water. The salt which crystallizes out isfiltered, washed, and dried.

A mixture of 24 parts of nitrobenzene and 4.4 parts of the aboveprepared di-o-tolylguanidine salt is heated to and treated with 2.5parts of cinnamoyl chloride. The mixture is then heated further to tocomplete the reaction, cooled to 85 and treated with a solution of 1.9parts of phenol in 5 parts of 5N sodium hydroxide. The resulting brightyellow precipitate is filtered, washed with nitrobenzene and acetone anddried.

Example19 H0: SOaH ([JOHN S NHOC 02 t; S NSO SOaN S i) W 0E! OC pared asdescribed above, parts of chlorobenzene, and

15.8 parts of pyridine is stirred and refluxed and graduallytreated with13.2 parts thiophene-Z-carboxylic acid chloride. After stirring andrefluxing for three hours the mixture is worked up in the usual manner,giving a product of pale yellow .color- Example 16 A mixture" of 250parts oftpyridine and 15.2 P111115s of 15.2 parts of p-anisic acid isadded gradually to 58 parts of chlorosulfonic acid at 5-11 C. Afterone-half hour the mixture is gradually warmed to 75 and maintained atthis temperature one hour. It is then cooled, drowned in ice, andfiltered. 10 parts of the resulting sulfonyl chloride is treated with 8parts of morpholine. The reaction mixture is slowly treated with 5 Nsodium hydroxide, the temperature rising to 25 After acidification withhydrochloric acid, the p-anisic acid m-sulfon morpholide is filtered. Itmelts at 218-9.

2.6 parts of this product is converted to the corresponding carboxylicacid chloride by treatment with 1.6 parts of thionyl chloride, in theusual manner. This is then added to a mixture of 12 parts ofnitrobenzene and 2.2 parts of the di-o-tolylguanidine salt preparedas inExampie 18. After twenty minutes at 140-5, the mixture is treated with asolution of 0.9 part of phenol in 2 parts of 5 N sodium hydroxide, withimmediate formation of 10 a yellow precipitate. The product is filteredin the hot, To 677 parts of 35% oleum is gradually added 105.3 washedwith nitrobenzene followed by acetone, and dried. parts of3,3'-dichlorobenzidine sulfate, the temperature 20 being maintainedbelow 20. The mixture is heated to 60 C. and maintained at thistemperature three The analogous disulfonanilide, which has similarprophours. It is then drowned in 1500 parts of ice and erties, isobtained in a similar way, substituting aniline a water. The precipitateis thoroughly washed, and then for morpholineinthe above procedure.dried at 75 C. This is the dichloro'diamino dib'enz'o- Example 21thiophene dioxide of the probable formula:

# 1 COHN N'Hoo S 00H; 2 CH:O 16 the position of the sulfone bridge notbeing clearly es- H038 som tablished.

Acylation is carried out as follows: To a stirred sus* pension of 15.8parts of the above prepared compound 0 CH OH in 147 parts of pyridine,there is gradually added- 34.5 20 parts of anisoyl chloride. Theresulting mixture is then 3.6 parts of 2,4-dimethoxybenzoic acid isconverted to refluxed until acylation is complete, as shown by the acidchloride by treatment m the usual way with 2.6 parts disappearance ofprimary amine groups. The reaction of thionyl chloride in the presenceof 8 parts of pyridine. mixture is drowned in 200 parts of-watercontaining 20 This is added at 30 to asolution of 2.0 parts of3,7-diparts of sodium carbonate, and filtered. The cake isaminodibenzothiophenedioxide in 49 parts of pyridine. thoroughly washedand dried at 75 C.

The product precipitates out and is filtered, washed With Sulfonation iscarried out by forming a suspension alcohol and water, and dried;Sulfonation is effected by of 16.1 parts of the above prepared compoundin 120 adding 2.7 parts of the resultingproduct to 11-12 parts parts ofnitrobenzene and gradually treating with 5.9

of chloro-sulfonic acid at minus8 to 0 C. and stirring parts ofchlorosulfonic acid. The mixture is stirred for for one and one-halfhours at amaximum temperature'of one-half hour at about C. and thenheated to 120 15". The mixture isthen drowned inice and filtered C. andkept at this temperature for one-half hour. and washed. The product isslurried'in water, neutralized The product is isolated by drowning inethanol, filtering, with sodium hydroxide solution, filtered, anddriedat 1l0. and Washing. It is a light-straw color powder, soluble Example22 Hots-Grammars S NHCOHN-Q-SOsH O:

A mixture of 2.5 parts of 3,7-diaminodibenzothioin water, and havingmarked substantivity for cellulosic phenedioxide and 5.7 partsof phenylisocyanate isheated fibers, to which it imparts a bright bluefluorescence at 125-30 until reaction is complete as shown by the underultraviolet hght.

Example 25 CH CH1 CHaQOCONH S -NHOOC OCHa S0 02 502E disappearance offreeamino groups. The reaction mix- 93.0 parts of tolidine sulfate isgradually added to ture is then diluted with acetone, filtered, washedwith 677.5"parts of 25% oleum, the temperature being kept acetone, anddried. 4.4 parts of the resulting product below 40 C. The mixture isthen heated to C.

is gradually added at approximately minus 5 to 21.2 over a one hourperiod, stirred at this temperature for parts of chlorosulfonic acid.After two hours at 0-5, 3 hours, then heated to. 120 C., kept at thistemperathe mixture is drowned in ice, salted with sodium chloture 2%hours, and finally heated for one-half hour ride, filtered, and washedwith brine. It is then disat 140 C. The reaction mixture is drowned in2000 solved in 75 parts of soda ash solution, salted with Z0 60 parts ofwater. The yellow disulfonic acid is filtered, parts of sodium chloride,heated to 80-90, filtered, washed, andd'ried. This intermediate has theprobable washed with brine, and dried. I formula:

Example 23 coon 0H 0H; I NH2 8 NH:

803B 02 SOZH H00? H03 301E COHN S 'N'HCO The exact location of all thesubstituents has not been determined. 21.7 parts of the disulfonieacidso-preparedis dis- A mixture of 3 parts of phthalic anhydride and 1.1solved in 196 parts of dry pyridine, treated with 26.0 parts of thedi-o-tolylguanidine salt, prepared as in 1521- parts of anisoylchloride,and refluxed for 3 hours. ample 18, is fused to a maximum temperature of220. The mixture isv then steam distilled in the presence of The mixtureis cooled to 55 and treated with a small sodium carbonate, to removepyridine. The light colquantity of nitrobenzene followed by 6 parts of10 N ored precipitate remaining isfilt'ered, Washed with 5% sodiumhydroxide and 6 parts of alcohol to precipitate sodium chloride solutionfollowed by icewater, and the yellow solid product, which is dried atdried.

Example 24 Example 26 I CEO cm omo-O-comz 244 parts of dianisidine isslurried in 315 parts of parts of water. The solution is cooled andfiltered to reglacial acetic acid and gradually treated with 236 partsof acetic anhydride. Acetylation is completed by refluxing, the mixturebeing cooled and filtered. The product, diacetyl dianisidine, melts atabout 243 C. after being washed with alcohol.

32.8 parts of the above prepared diacetyl dianisidine is graduallydissolved in 330 parts of 35% oleum at -30" C. The solution is slowlyheated to 60 C. and stirred at this temperature for three hours. Theresulting dark red solution is drowned in 1600 parts of ice and water.The resulting solution is heated to 95-100 C. for one hour, cooled toroom temperature, and filtered. The yellow product is washed withethanol and dried.

Acylation is effected by heating at 100 C. for one hour a mixture of 5.1parts of the above prepared compound, 29.3 parts of pyridine, and 6.9parts of anisoyl chloride. The reaction mixture is drowned in 100 partsof water, made alkaline with 10% sodium carbonate solution, and theproduct filtered, washed, and dried. When treated with an aqueoussolution of this product, cotton cloth acquires an intense greenish-bluefluorescence under ultraviolet light.

Example 27 A mixture of 28.2 parts of benzidine sulfate and 211.2 partsof 26.8% oleum is heated at 70 C. for 2 hours, cooled to about 40 C.,and treated with 46.0 parts of 86.3% sulfuric acid. The mixture is thenheated to about 140 C., stirred at thistemperature for about 18 hours,and finally for 2,hours at about 180 C. The reacted mixture is drownedin 1,000 parts of water, cooled, and filtered. The filter cake isslurried in 500 parts of water, neutralized to a pH of 7 by the additionof triethylamine, and filtered. On acidification with 5 N sulfuric acid,the 3,7-diaminodibenzothiophenedioxide- Z-sulfonic acid separates fromsolution. The resulting mixture is filtered at the boil, and the productwashed with water and dried.

A mixture of 12.8 parts of the above prepared prodnet, 110 parts ofchlorobenzene, 25 parts of pyridine, and 31 parts of anisoyl-chloride isrefluxed for 24 hours, or until acylation is complete, as shown by thedisappearance of primary amino groups. The reaction mixture is thenfreed of pyridine and chlorobenzene by steam distillation in thepresence of sodium carbonate. The product is salted out with sodiumchloride, washed with 2% brine, and dried at 100 .C. An excellent yieldof a pale colored solid is obtained. The product is sparingly soluble inwater, and shows, even from very dilute solutions, a marked aflinity forcellulosic fibers,

to which it imparts a bright bluish-white fluorescence under ultravioletirradiation.

HBO 01H NH 8 NH: 0:

is recrystallized from water.

To a stirred refluxing slurry of 5.6 parts of the above preparedtriethylamine salt, 77 parts of chlorobenzene, and 6.7 parts ofpyridine, is gradually added 6.9 parts of anisoyl chloride. Stirring andrefluxing are continued until acylation is complete .The mixture is thenfreed of solvents by steam distillation in the presence of sodium NHG000cm carbonate, and the cream-yellow product salted out of solution bythe additionof sodium chloride.

Example 29 a-CmH1CONH s NHCOCmHT-fl O:

finally ice water. There results an excellent yield of product.

Example 30 01110 ocu;

66 parts of diacetyl dianisidine (as prepared in Example 27) isgradually added to 660 parts of 35 oleum,

soiH

A mixture of 14.1 parts of benzidine sulfate and 113 parts of 25% oleumis heated at 70 C. for two hours,

then rapidly heated to 140 C. and maintained at this temperature for 3hours. It is then drowned in 600 parts of ice, followed by 10.1 parts oftriethylamine and then slowly heated to 60 C., kept at this temperaturethree hours, and drowned in 3000 parts of ice and water. After one hourat 15 C., a colorless precipitate forms, which is filtered out; Highertemperatures should be 500 avoided to prevent hydrolysis of themonoacetyl group.

13 T4 The product is filtered and'w hed with ethanol followedwherein"'RCO and RC'O' ar'el 'caj'thoxyiieacyr rad} by benzene. It isdried at"75C. cals and X1, X2, X3, X4, X5, ana' xeere eeieexerrrem thegroup consisting of the H, SOsH, halogen, lower GHeO H; alkyl and lowerjalkoxy' radicals, not more" than two of 5 .Xs'being sulfonate radicals,and at least oneof R and R containing a-sulfonate radieahwhennoneof'thej are sulfonate radicals. Y GHCONH 2. A method of whitening andbrightening fabrics s which comprises treating the fabric with asulfonated dibenzothiophene dioxide according to claim 1 in which thecarboxylic acyl radicals are of aromatic carboxylic A mixture of 8.6parts of the above-prepared comacids pound, 80 parts of pyridine, and6.9'parts of -aniso l chloride is refluxed until acylation is complete.The rea f Wln-temng brkghtemng fabncs tion mixture is then drowned in asolution of sodium P fabnc Wlth a compound chloride and sodiumcarbonate, containingenough ice to l5'accord}ngflto 3 25111 Whlch atleast one of RC0 keep the temperature in the range 10 to 15 C. The lightand R CO contams aslllfoflate substltQemyellow product is filtered,washed with brine, and dried A method of {hltenlng a11d brlghtenmgfabllcs at 75 C. It imparts fluorescence to cotton cloth. Whlch Pompnsesf g the W1t h a P The products described may be incorporated directlyaccordmg to 9131111 2 111 Whlch the dlbefllmhlophene in paper ul theamount dependent 11 th degree of nucleus contains at least one sulfonatesubst tuent. brightening effect desired. Generally this amount will AmethPd 0f b g aud brightenin fabflcs vary between .02% and ,2% of thedry weight f th which comprises treating the fabric with an aqueouspulp. Sized pulp shows generally better retention than solutioncontaining from about 0.001% to about 1% unsized pulp, especially inconcentrations higher than of a compound of the formula YOtS sOzY about.075 but unsized pulp shows somewhat higher wherein Y is selected fromthe group consisting of H, brightening efiect for equal amounts ofbrightener. The NH; and the alkali metal radicals.

resulting papers show bright fluorescence of a rather 6. A method ofwhitening and brightening fabrics greenish hue. Alternatively, thesebrighteners may be which comprises treating the fabric with an aqueousapplied from aqueous or alcoholic aqueous solution by solutioncontaining from about 0.001% to about 1% staining the finished papersheet, or they may be incorof a compound of the formula CHzO YO: SOzYOCH: CEO-*QCOHN s NHCO-C -OCH2 0:

porated in surface sizing such as a starch, gelatine, or 0 wherein Y isselected from the group consisting of the like. 5 H, NH4 and the alkalimetal radicals.

These products may be applied to textile materials by 7. A method ofwhitening and brightening fabrics the following procedure: whichcomprises treating the fabric with an aqueous The product is dissolvedin 25,000 times its weight of solution containing from about 0.001% toabout 1% water, and 300 parts of the resulting solution is added to of acompound of the formula 8,000 parts of 0.5% soap solution, followed by1,700 parts of water additional. The resulting bath is used to launder500 parts of white cotton cloth in the ordinary Way at 130 F. When thelaundering is completed, the YO=S SOs fabric is rinsed at 75 F. anddried at 160 F. The resulting cloth, when compared with the same fabriclaun- COHN NHQQ dered in the same way except for the omission of bright-B ener, shows markedly superior Whitening in daylight.

Under direct ultraviolet illumination, the fabric shows strongfluorescence, of a shade which varies somewhat from product to product,but is generally of a rather greenish hue. he Y l t d fr th Theseproducts vary among themselves in brightening 12 11-1: 3 2113 g difflgfconslstmg of power. Alkoxy and alkyl substitutionmthe aroyl nuclei 3 Amethod f whitening d b i ht i f b i tends to increase this power andamong the best products which comprises treating the f b i with an aqueous 111 this respect are those of Examples 1, 3, and solutioncontaining from; about 0.001% to about 1% We claim: d f 1. A method ofwhitening and brightening fabrics a the immula which comprises treatingthe fabric with an aqueous solution containing from about 0.001% toabout 1% of a sulfonated dibenzothiophene dioxide selected from C1130YOaS SO:|Y OCH: the group of sulfonic acids and containing the nucleusCHa- COHN NHCO -CH: x0 Xi wherein Y is selected from the groupconsisting of H, RCOHN s NHOCB' NH; and the alkali metal radicals.

9. A method of whitening and brightening fabrics x, which comprisestreating the fabric with an aqueous 1 16 sqlution pontaining from jahout0.001% to about 1% wherein Y is selected from the group consisting of H,'of a compound of the formula NH; and the alkali metal radicals.

so? 9 son:

OHIO 001m B NHCO 0cm References Cited in the file of this patent UNITEDSTATES PATENTS 2,619,470 Hendrix Noy. 25, 1952

1. A METHOD OF WHITENING AND BRIGHTENING FABRICS WHICH COMPRISESTREATING THE FABRIC WITH AN AQUEOUS SOLUTION CONTAINING FROM ABOUT0.001% TO ABOUT 1% OF A SULFONATED DIBENZOTHIPHENE DIOXIDE SELECTED FROMTHE GROUP OF SULFONIC ACIDS AND CONTAINING THE NUCLEUS